A well known type of bedding product comprises a motorized adjustable bed in which an articulated frame supports a mattress. These motorized adjustable beds have traditionally been used in hospitals but more and more are being installed and used in residential homes. Motorized articulated beds have conventionally had an upper body support movable between an inclined position in which it supports the patient in a sitting position and a prone position in which the patient lies down in a generally horizontal position. In addition, a leg support is movable between positions and may be adjusted to a desired degree of inclination. An actuating mechanism, commonly two or more electric motors, raises and lowers the head and leg supports of the articulated bed frame. U.S. Pat. No. 5,640,730 discloses such an articulated bed. Disadvantages of adjustable beds incorporating two electric motors over adjustable beds having only one electric motor include 1) the odds of at least one of the motors malfunctioning increases and 2) increased manufacturing costs.
In order to reduce the manufacturing costs of an adjustable bed, adjustable beds have been made with a single motor. U.S. Pat. Nos. 4,385,410 and 4,559,655 discloses such adjustable beds powered by a single motor. Some known adjustable beds powered by a single motor require a great deal of power to raise and lower the bed sections to their desired positions due to the weight of the person lying on the bed.
U.S. Pat. Nos. 6,499,162 and 6,640,365 disclose adjustable beds comprising a plurality of bedplates pivotally secured together for supporting a mattress. Connecting elements or links pivotally connect a base to the bed plates. A movable member slides along the base and is activated by a piston movable from inside a cylinder secured to the base. Activation of a power source such as an electric motor causes movement of the bed plates via movement of the sliding member. One disadvantage with such adjustable beds is that the slidable member may be jammed or trapped and unable to slide along the base. If this occurs, activation of the piston may damage or break one or more of the elements of the adjustable bed.
Therefore, there is a need for an improved articulated bed powered by a linear actuator which moves a frame above a stationary base using rollers.